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  <section id="module-mailcap">
<span id="mailcap-mailcap-file-handling"></span><h1><a class="reference internal" href="#module-mailcap" title="mailcap: Mailcap file handling."><code class="xref py py-mod docutils literal notranslate"><span class="pre">mailcap</span></code></a> — Mailcap file handling<a class="headerlink" href="#module-mailcap" title="Permalink to this headline">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.9/Lib/mailcap.py">Lib/mailcap.py</a></p>
<hr class="docutils" />
<p>Mailcap files are used to configure how MIME-aware applications such as mail
readers and Web browsers react to files with different MIME types. (The name
“mailcap” is derived from the phrase “mail capability”.)  For example, a mailcap
file might contain a line like <code class="docutils literal notranslate"><span class="pre">video/mpeg;</span> <span class="pre">xmpeg</span> <span class="pre">%s</span></code>.  Then, if the user
encounters an email message or Web document with the MIME type
<em class="mimetype">video/mpeg</em>, <code class="docutils literal notranslate"><span class="pre">%s</span></code> will be replaced by a filename (usually one
belonging to a temporary file) and the <strong class="program">xmpeg</strong> program can be
automatically started to view the file.</p>
<p>The mailcap format is documented in <span class="target" id="index-0"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc1524.html"><strong>RFC 1524</strong></a>, “A User Agent Configuration
Mechanism For Multimedia Mail Format Information”, but is not an Internet
standard.  However, mailcap files are supported on most Unix systems.</p>
<dl class="function">
<dt id="mailcap.findmatch">
<code class="sig-prename descclassname">mailcap.</code><code class="sig-name descname">findmatch</code><span class="sig-paren">(</span><em class="sig-param">caps</em>, <em class="sig-param">MIMEtype</em>, <em class="sig-param">key='view'</em>, <em class="sig-param">filename='/dev/null'</em>, <em class="sig-param">plist=[]</em><span class="sig-paren">)</span><a class="headerlink" href="#mailcap.findmatch" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a 2-tuple; the first element is a string containing the command line to
be executed (which can be passed to <a class="reference internal" href="os.html#os.system" title="os.system"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.system()</span></code></a>), and the second element
is the mailcap entry for a given MIME type.  If no matching MIME type can be
found, <code class="docutils literal notranslate"><span class="pre">(None,</span> <span class="pre">None)</span></code> is returned.</p>
<p><em>key</em> is the name of the field desired, which represents the type of activity to
be performed; the default value is ‘view’, since in the  most common case you
simply want to view the body of the MIME-typed data.  Other possible values
might be ‘compose’ and ‘edit’, if you wanted to create a new body of the given
MIME type or alter the existing body data.  See <span class="target" id="index-1"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc1524.html"><strong>RFC 1524</strong></a> for a complete list
of these fields.</p>
<p><em>filename</em> is the filename to be substituted for <code class="docutils literal notranslate"><span class="pre">%s</span></code> in the command line; the
default value is <code class="docutils literal notranslate"><span class="pre">'/dev/null'</span></code> which is almost certainly not what you want, so
usually you’ll override it by specifying a filename.</p>
<p><em>plist</em> can be a list containing named parameters; the default value is simply
an empty list.  Each entry in the list must be a string containing the parameter
name, an equals sign (<code class="docutils literal notranslate"><span class="pre">'='</span></code>), and the parameter’s value.  Mailcap entries can
contain  named parameters like <code class="docutils literal notranslate"><span class="pre">%{foo}</span></code>, which will be replaced by the value
of the parameter named ‘foo’.  For example, if the command line <code class="docutils literal notranslate"><span class="pre">showpartial</span>
<span class="pre">%{id}</span> <span class="pre">%{number}</span> <span class="pre">%{total}</span></code> was in a mailcap file, and <em>plist</em> was set to
<code class="docutils literal notranslate"><span class="pre">['id=1',</span> <span class="pre">'number=2',</span> <span class="pre">'total=3']</span></code>, the resulting command line would be
<code class="docutils literal notranslate"><span class="pre">'showpartial</span> <span class="pre">1</span> <span class="pre">2</span> <span class="pre">3'</span></code>.</p>
<p>In a mailcap file, the “test” field can optionally be specified to test some
external condition (such as the machine architecture, or the window system in
use) to determine whether or not the mailcap line applies.  <a class="reference internal" href="#mailcap.findmatch" title="mailcap.findmatch"><code class="xref py py-func docutils literal notranslate"><span class="pre">findmatch()</span></code></a>
will automatically check such conditions and skip the entry if the check fails.</p>
</dd></dl>

<dl class="function">
<dt id="mailcap.getcaps">
<code class="sig-prename descclassname">mailcap.</code><code class="sig-name descname">getcaps</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#mailcap.getcaps" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns a dictionary mapping MIME types to a list of mailcap file entries. This
dictionary must be passed to the <a class="reference internal" href="#mailcap.findmatch" title="mailcap.findmatch"><code class="xref py py-func docutils literal notranslate"><span class="pre">findmatch()</span></code></a> function.  An entry is stored
as a list of dictionaries, but it shouldn’t be necessary to know the details of
this representation.</p>
<p>The information is derived from all of the mailcap files found on the system.
Settings in the user’s mailcap file <code class="file docutils literal notranslate"><span class="pre">$HOME/.mailcap</span></code> will override
settings in the system mailcap files <code class="file docutils literal notranslate"><span class="pre">/etc/mailcap</span></code>,
<code class="file docutils literal notranslate"><span class="pre">/usr/etc/mailcap</span></code>, and <code class="file docutils literal notranslate"><span class="pre">/usr/local/etc/mailcap</span></code>.</p>
</dd></dl>

<p>An example usage:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">import</span> <span class="nn">mailcap</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">d</span> <span class="o">=</span> <span class="n">mailcap</span><span class="o">.</span><span class="n">getcaps</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">mailcap</span><span class="o">.</span><span class="n">findmatch</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="s1">&#39;video/mpeg&#39;</span><span class="p">,</span> <span class="n">filename</span><span class="o">=</span><span class="s1">&#39;tmp1223&#39;</span><span class="p">)</span>
<span class="go">(&#39;xmpeg tmp1223&#39;, {&#39;view&#39;: &#39;xmpeg %s&#39;})</span>
</pre></div>
</div>
</section>


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